To enter the Temple, teleport by way of Teleporter Hiraine in Dratan (1588,1741). Using a Dratan NPC scroll will get you to that teleporter.
Monsters: Cursed Spider x 30
Other: Dusty Chest
What to do: Kill all the spiders then open the Dusty Chest (similar to processing Green Leaves or Quality Stones).
What is inside the chest:

Ancient Key 1 [1] (one of the four keys needed to open the Ancient Chest)
Note: If you try to open the Dusty Chest before killing the spiders around it, they will start attacking you and you will stop opening the chest.
Other SS's: (click with scroll wheel to open in new tab)
After spiders are deadAfter opening the chest .
Monsters: Cursed Spider x 27
Other: Broken Chest
What to do: Kill all the spiders then open the Broken Chest (similar to processing Green Leaves or Quality Stones).
What is inside the chest:

Ancient Key 2 [1] (one of the four keys needed to open the Ancient Chest)
Note: If you try to open the Broken Chest before killing the spiders around it, they will start attacking you and you will stop opening the chest.
Other SS's: (click with scroll wheel to open in new tab)
After opening the chest
Monsters: Cursed Spider x 11, Wane Spider x 17
Other: Cobwebbed Chest
What to do: Kill all the spiders then open the Cobwebbed Chest (similar to processing Green Leaves or Quality Stones).
What is inside the chest:

Ancient Key 3 [1] (one of the four keys needed to open the Ancient Chest)
Note: If you try to open the Cobwebbed Chest before killing the spiders around it, they will start attacking you and you will stop opening the chest.
Other SS's: (click with scroll wheel to open in new tab)
After opening the chest.
Monsters: Wane Spider x 1
Other: Unidentified Chest
Note: This chest is attackable and will spawn pots upon it "dying"
Pots that the chest has been known to spawn:

Great Healing Potions,

Great Mana Potions,

Small Attack Potions,

Small Defense Potions,

Polluted Air Cure [1] (always)
Example of what drops:
.
Other SS's: (click with scroll wheel to open in new tab)
After chest is opened
Monsters: Cursed Spider x 12, Wane Spider x 16
Other: Hidden Chest
What to do: Kill all the spiders then open the Hidden Chest (similar to processing Green Leaves or Quality Stones).
What is inside the chest:

Ancient Key 4 [1] (one of the four keys needed to open the Ancient Chest)
Note: If you try to open the Hidden Chest before killing the spiders around it, they will start attacking you and you will stop opening the chest.
Other SS's: (click with scroll wheel to open in new tab)
After opening the chest
Monsters: Wane Spider x 1, Temple Specimen Zombie x 15, Temple Specimen Corpse x 10, Temple Specimen Child x 10, Temple Specimen Boomer x 7
Other SS's: (click with scroll wheel to open in new tab)
Another view of the room after it's been cleared
Monsters: Legendary Slayer x 6, Twin Hadian x 6, Curd Hadian x 4
See
2 below.

Other: Half-Opened Chest
Note: This chest is attackable and will spawn pots upon it "dying"
Pots that the chest has been known to spawn:

Great Healing Potions,

Great Mana Potions,

Small Attack Potions,

Small Defense Potions
Example of what drops:

Other SS's: (click with scroll wheel to open in new tab)
After chest is opened
Monsters: Temple Specimen Cadaver x 8, Twin Hadian x 2, Barren Eise x 1, Small Barren Eise x 2, Tiny Barren Eise x 8 (Barren Eise spawns 2 Small Barren Eise, and each Small Barren Eise spawns 4 Tiny Barren Eise)
Other: Ancient Chest
Note: This chest is attackable and will spawn an Ancient Chest upon it "dying"
What is inside the chest:

Ancient Chest
What might be inside the Ancient Chest:

[T]The Forgotten Relic(1) - Titan Erraticrat gear

[H]The Forgotten Relic(1) - Healer Erraticrat gear

[N]The Forgotten Relic(1) - Knight Erraticrat gear

[M]The Forgotten Relic(1) - Mage Erraticrat gear

[R]The Forgotten Relic(1) - Rogue Erraticrat gear

[S]The Forgotten Relic(1) - Sorcerer Erraticrat gear

Large Attack Potion x 10
................................................................................................................................................................ 
Large Defense Potion x 10

Monsters: Curd Hadian x 6, Legendary Slayer x 12, Twin Hadian x 4
Other SS's: (click with scroll wheel to open in new tab)
First cornerLong hallSecond corner
Monsters: Curd Hadian x 14, Legendary Slayer x 6, Twin Hadian x 7, Blood Terrain x 1
See
3 below.
Other SS's: (click with scroll wheel to open in new tab)
Blood Terrain boss in center
Other: Half-Opened Chest
Note: This chest is attackable and will spawn pots upon it "dying"
Pots that the chest has been known to spawn:

Great Healing Potions,

Great Mana Potions
Other SS's: (click with scroll wheel to open in new tab)
After chest is opened
Monsters: Curd Hadian x 3, Twin Hadian x 1

Monsters: Cursed Spider x 12 (spawned by "killing" Unopened chest)
Other: Unopened Chest that spawns 12 Cursed Spiders
Other SS's: (click with scroll wheel to open in new tab)
Unopened Chest in middle of roomAfter chest is opened
ToF NPC
Monsters: Jumping Devil x 6, Transformed Jumping Devils x 4, Legendary Slayer x 6, Transformed Legendary Slayer x 9
Caution: Traps, similar to Monster Combo, take a considerable amount of HP. Usually more than one trap is on one spot
Other SS's: (click with scroll wheel to open in new tab)
Traps on bridgeTraps exploding on bridge 1Traps exploding on bridge 2
Monsters: Transformed Legendary Slayer x 6, Erraticrat x 1, Transformed Jumping Devil x 8 (Erraticrat spawns 8 Transformed Jumping Devils when near death)
See
4 below.
Note: After killing Erraticrat, two NPCs spawn, one that will teleport you outside the Temple of Forgetfullness.
Other SS's: (click with scroll wheel to open in new tab)
Erraticrat in middleSpawned Transformed Jumping DevilsNPCs that spawn after killing Erraticrat
Other: Half-Opened Chest
Note: This chest is attackable and will spawn pots upon it "dying"
Other SS's: (click with scroll wheel to open in new tab)
After chest is opened